Light therapy is a way to treat seasonal affective disorder (SAD) by exposure to artificial light. Seasonal affective disorder is a type of depression that occurs at a certain time each year, usually in the fall or winter.

During light therapy, you sit or work near a device called a light therapy box. The box gives off bright light that mimics natural outdoor light.

Light therapy is thought to affect brain chemicals linked to mood, easing SAD symptoms. Using a light therapy box may also help with other types of depression, sleep disorders and other conditions. Light therapy is also known as bright light therapy or phototherapy.

You may want to try light therapy for a number of reasons:

It's a proven seasonal affective disorder treatment.

You have another condition, such as nonseasonal depression or insomnia, and your doctor recommends it.

You want to try treatment that is safe and has few side effects.

You want to increase the effectiveness of antidepressant medication or mental health counseling (psychotherapy).

You need to avoid antidepressant medications during pregnancy or while breast-feeding.

It may allow you to take a lower dose of antidepressant medication.

Light therapy for conditions other than SAD

In addition to seasonal affective disorder, light therapy is used as a treatment for other conditions, including:

Types of depression that don't occur seasonally

Jet lag

Sleep disorders

Adjusting to a nighttime work schedule

Dementia

Light therapy is also used to treat skin conditions such as psoriasis. However, this is different from the type of light therapy used for SAD and the other conditions above. Light therapy for skin disorders uses a lamp that emits ultraviolet (UV) light. This type of light is filtered out in light therapy boxes because it can damage the eyes and skin.

Light therapy is generally safe. If side effects occur, they're usually mild and short lasting. They may include:

When side effects do occur, they may go away on their own within a few days of starting light therapy. You also may be able to manage side effects by reducing treatment time, moving farther from your light box, taking breaks during long sessions or changing the time of day you use light therapy. Talk to your doctor for additional advice, or if side effects don't go away or get worse.

When to use caution

It's always a good idea to talk to a doctor before starting light therapy, but it's especially important if:

You have a condition that makes your skin especially sensitive to light, such as systemic lupus erythematosus

You take medications that increase your sensitivity to sunlight, such as certain antibiotics, anti-inflammatories or the herbal supplement St. John's Wort

You have an eye condition that makes your eyes vulnerable to light damage

You have a history of skin cancer

Ultraviolet light

Light therapy boxes should be designed to filter out harmful ultraviolet (UV) light, but some may not filter it all out. This type of light can cause skin and eye damage. Look for a light therapy box that emits as little UV light as possible. If you have concerns about light therapy and your skin, talk to your dermatologist.

Tanning beds: Not an alternative to light therapy

Some people claim that tanning beds help ease seasonal affective disorder symptoms. But this hasn't been proved to work. Visible light, not the UV light released by tanning beds, is used in light therapy. The type of light released by tanning beds can damage your skin and increase your risk of skin cancer.

Caution for bipolar disorder

Light therapy may trigger mania in some people with bipolar disorder. If you have any concerns about how light therapy may be affecting your mood or thoughts, seek help right away.

Although it's possible to do light therapy on your own, it's best to ask your doctor or mental health provider if it's a good option for you. Also ask whether you need to take any special precautions. This guidance can help you get the most benefit and minimize possible side effects.

Talk with your doctor about the best light therapy box for you, and familiarize yourself with the variety of features and options to help ensure that you buy a high-quality product that's safe and effective.

Starting light therapy

Generally, most people with seasonal affective disorder begin treatment with light therapy in the early fall, when it typically becomes cloudy in many regions of the country. Treatment usually continues until spring, when outdoor light alone is sufficient to sustain a good mood and higher levels of energy.

If you typically have fall and winter depression, you may notice symptoms during prolonged periods of cloudy or rainy weather during other seasons. You and your doctor can adjust your light treatment based on the timing and duration of your symptoms.

If you want to try light therapy for nonseasonal depression or another condition, talk to your doctor about how light therapy can be most effective.

During light therapy

During light therapy sessions, you sit or work near a light box. To be effective, light from the light box must enter your eyes indirectly. You can't get the same effect merely by exposing your skin to the light. While your eyes must be open, don't look directly at the light box, because the bright light can damage your eyes. Be sure to follow your doctor's recommendations and the manufacturer's directions.

Three key elements for effective light therapy

Light therapy is most effective when you have the proper combination of duration, timing and light intensity:

Duration. When you first start light therapy, your doctor may recommend treatment for shorter blocks of time, such as 15 minutes. You gradually work up to longer periods. Eventually, light therapy typically involves daily sessions ranging from 30 minutes to two hours, depending on your light box's intensity.

Timing. For most people, light therapy is most effective when it's done early in the morning, after you first wake up. Your doctor can help you find the light therapy schedule that works best.

Intensity. The intensity of the light box is recorded in lux, which is a measure of the amount of light you receive at a specific distance from a light source. Light therapy boxes usually produce between 2,500 lux and 10,000 lux. The intensity of your light box affects how far you sit from it and the length of time you need to use it. A 10,000-lux light box usually requires 30-minute sessions, while a 2,500-lux light box may require two-hour sessions.

Finding time for light therapy

Light therapy requires time and consistency. You can set your light box on a table or desk in your home or office. That way you can read, use a computer, write, watch TV, talk on the phone or eat while having light therapy. But stick to your therapy schedule and don't overdo it.

Some light boxes are even available as visors that you can wear, although their effectiveness isn't proved.

Light therapy probably won't cure seasonal affective disorder, depression or other conditions. But it may ease symptoms, increase your energy levels, and help you feel better about yourself and life.

Light therapy can start to improve symptoms within just a few days. In some cases, though, it can take two or more weeks.

Getting the most out of light therapy

Light therapy isn't effective for everyone. But you can take steps to get the most out of your light therapy and help make it a success.

Get the right light box. Do some research and talk to your doctor before buying a light therapy box. That way you can be sure your light box is safe, the right brightness, and that its style and features make it convenient to use.

Be consistent. Stick to a daily routine of light therapy sessions to help ensure that you maintain improvements over time. If you simply can't do light therapy every day, take a day or two off, but monitor your mood and other symptoms — you may have to find a way to fit in light therapy every day.

Time it right. If you interrupt light therapy during the winter months or stop too soon in the spring when you think you're improving, your symptoms could return.

Include other treatment. If your symptoms don't improve enough with light therapy, you may need additional treatment. Talk to your doctor about other treatment options, such as psychotherapy or antidepressants.

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